You can't install it easily without some non-free software. When you download the iso it is precontaminated. You can add a special boot flag to turn off non-free firmware but that's rather obscure.
I'm not against a non-free iso, I just want to have the option for both.
They used to omit non-free-firmware from the installation. They changed it with Debian bookworm when they split the firmware out of non-free, since unfortunately a LOT of hardware requires non-free firmware of some sort. There's also things like CPU microcode in there, which practically everyone needs to ensure CPU vulnerabilities are patched.